Apparatus and method of making pneumatic air springs



Feb. 14, 1961 H. H. DEIST ETAL APPARATUS AND METHOD OF MAKING PNEUMATIC AIR SPRINGS 5, 1956 10 Sheets-Sheet 1 Filed Dec.

FIG.I

INVENTORS HERBERT H. DEIST BY JACK L. HOLLIS ATTY Feb. 14, 1961 H. H. DEIST EI'AL 2,

NGS

l0 Sheets-Sheet 2 APPARATUS AND METHOD OF MAKING PNEUMATIC AIR SPRI 5, 1956 Filed Dec.

Feb. 14, 1961 H. H. DEIST ETAL 2,971,875

, APPARATUS AND METHOD OF MAKING PNEUMATIC AIR SPRINGS Filed Dec. 5, 1956 10 Sheets-Sheet 3 FIG. 7

By JACK L. HOLLIS ATTY.

Feb. 14, 1961 H. H. DEIST ETAL 2,971,875

APPARATUS AND METHOD OF MAKING PNEUMATIC AIR SPRINGS Filed Dec. 5, 1956 10 Sheets-Sheet 4 FIG. 8

' INVENTORS HERBERT H. DEIST By JACK L.HOLLIS Q/QZzaM/L ATTY.

Feb. 14, 1961 H. H. DEIST ETAL 2,971,875

APPARATUS AND METHOD OF MAKING PNEUMATIC AIR SPRINGS Filed Dec. 5, 1956 1O Sheets-Sheet 5 FIG. ll

44 A 7/22 ,//7 1/ //6 a2 a5 a? v w .J FIGJB /0 do 0 O 37 INVENTORS HERBERT H.DEIST BY JACK HOLLIS Way (44W AT TY.

Feb. 14, 1961 H. H. DEIST EI'AL 2,971,875 APPARATUS AND METHOD OF MAKING PNEUMATIC AIR SPRINGS v Filed Dec. 5, 1956,

IO'Sheets-Sheet 6 AT TY Feb. 14, 1961 H. H. DEIST ETAL 2,971,375

APPARATUS AND METHOD OF MAKING PNEUMATIC AIR SPRINGS Filed Dec. 5, 1956 10 Sheets-Sheet 7 BY JACK L. HOLLIS 3.9

g1/ QV W NTORS HERBER'I I fDEIST ATTY.

Feb. 14, 1961 H. H. DEIST EIAL 2,971,875

APPARATUS AND METHOD OF MAKING PNEUMATIC AIR SPRINGS Filed Dec. 5, 1956 10 Sheets-Sheet 8 INVENTORS HERBERT H. DEIST By JACK L. HOLLIS Q QZMA ATTY.

Feb. 14, 1961 H. H. DEIST EIAL 2,971,875

APPARATUS AND METHOD OF MAKING PNEUMATIC AIR SPRINGS Filed Dec. 5, 1956 10 sheets sheet 9 PIC-3.24 m 12a INVENTORS HERBERT H. DEIST BY JACK L.H OI LIS AT TY.

Feb. 14, 1961 H. H. DEIST ETAL 2,971,875

APPARATUS AND METHOD OF MAKING PNEUMATIC AIR SPRINGS Filed D80. 5, 1956 10 Sheets-Sheet 10 FIG. 26

INVENTORS HERBERT H. DEIST BY JACK HOLLIS ATTY.

Unite Sara. Paa .e -i

I 2,971,875 APPARATUS AND METHOD OF MAKING PNEUMATIC AIR SPRINGS Filed Dec. 5, 1956, Ser. No. 626,808 14 (Zlaims. (Cl. 154-83)' This invention relates to pneumatic bellows of the type known as air springs and more particularly to an improved method and apparatus for manufacturing such 2' air springs.

A recently developed air spring which is especially useful in automotive wheel suspensions consists of a single convolution body terminating in beads having ap preciably different diameters so that the smaller bead is capable ofpassing toward and through the larger bead in a telescoping movement when the air spring is deflected in service. The air spring is filled with air under pressures which are usually in the range of about 70-80 pounds per square inch, but which. often attain levels in the range of 100 to 150 pounds per square inch. Such an air spring requires a suflicient flexibility to undergo the above-mentioned telescoping movement for a great'many cycles and musthave-amechanical strength adequate to retain the highest fluid pressures to which it may be subjected. These requirements of flexibility and-of mechanicalstrength are in large measure incompatible with each other and are difficult to obtain in an air spring of this design except by the most favorable methods of manufacture.

According to the present invention, an air spring having these properties is manuractured by assembling plies of essentially weftless fabric in the form of a cylindrical body on a building drum having a diameter intermediate the diameters of thelarge and smallbeads.

One end of the body is turned radially inwardly'over the adjacent end of the building drum to a small diameter in order thatit may receive and be wrapped around the core of the small bead. This ply-contracting operation crowds the cords of the fabric plies together and is performed in a manner to minimize wrinkling of the fabric plies in that area, forthe presence of wrinkles will detract from the flexibility and strength of the spring.

The plies at' the other end of the air spring are expanded outwardly to a larger diameter in order that they may be wrapped'about and anchored to the core of the larger bead. In this operation, the cords of the plies become more widely spaced and this operation is done in such a manner as to produce a uniform spacing of the cords; This is important because the mechanical strength and imperviousness of this expanded portion of the air spring depends, in part, upon the rubber which bridges across adjacent cords and nonuniform spacing of the cords might well result in' locally weak areas.

, Accordingly, it a general object of the invention to provide van improved apparatus and method for manufacturingsuch air springs.

Another object is to provide apparatus forexpandingthe fabric pliesof a cylindrical air springbody into a flaring form. 1

Another object is to provide improved means fol-"con tracting rubberized fabric plies having an initial cylinforminto inwardly extendingflanged form.

Another object is to provide improved means for turning fabric plies about inextensible bead rings to form compact and strong bead structures.

Yet another object is to provide a method of building an air spring which consists in first assembling air spring plies incylind'rical form and then expanding and con tracting the plies" at opposite ends to form a body of flaring bell-shaped form.

Further objects are to provide an apparatus for manufacturing air springs which is simple and 'eifective in de-' sign which is virtually'automatic in operation, requiring minimum skill inits use; which rugged in service, requiring a minimum of maintenance.

Th ese and further objects and advantages will more fully appear from thefollowing description of a preferred form of the invention, reference being had to the accompanying drawings in which:

Figure 1 is a front elevation, partly in section, of an air spring manufactured according to the present invent-ion and shown assembled in a typical front wheel sus pension of an automobile;

Figure 2 is a perspective view of an unvulcanized single convolution air spring, of the type shown in Fig-. ure 1, just after it has been removed from the building drum prior to the molding and vulcanizing operation;

Figure 3 is a top elevation of an air spring building drum and associated apparatus embodying the present invention;

Figure 4 is a side elevation of ure 3; 1

Figure 5 is a longitudinal sectional view, on an enthe apparatus of Figlarged scale, of'the air spring building drum of Figures? 3" and 4; with the fabric body' plies shown in place on; the drum, the view being taken in the plane indicated.

by the lines 5 -5 in Figure 3;

Figure 6 is a fragmentary view showing the portion to the left of the drum of Figure 5;

Figure 7is a view on a so'rnewhat larger scale than that of Figure 5 showing the; right hand portion of the buildiilg'di'tlfll;-

Figures 8-1?- are diagrammatic longitudinal sectional viewsillust-rating the various stepsf in" the operation ofthe drum;

, Figure 8 shows the plies assembled'on the drum with" to be moved into the ply-contracting mechanism about position at the end of the fabric plies;

Figure 9 showsthe' manner in which the plies are: turned radially inwardly over the right end ofthe build-' ingdri'nfn by" the ply-contracting mechanism;

Figure 10 shows the setting of a' bead ring against:

the 'inturned plies;-

Figure 11 shows the inturhed plies turned out into cylindrical'formby a ply-stitching bag, the bag being moved into position to turn up the plies outwardly about the bead;

Figure 12 shows the -ply-stitching bag partially expanded to begin the turn-up of plies outwardly around;

the bead ring;

.Figure 13 shows the ply-stitching bag" fully expanded" and the plies turned and'stitched about the bead ring; 1 Figure 14 shows'the left-hand portion of the building drum expanded to force the body plies outwardly into positionto'engage a second bead ring of large diameter as compared to the first;

Figure IS shows the manner in which .a ply-turning sleeve engages and turns the expanded ends of the body plies inwardly about the large bead ring;

7 Figure 16 showsthe manner in which a' stitching roll finishes the ply-turning operation about the large bead ring; 7 I

Figure 1I- is a' sectional view "showing the ply-contract;

taken as indicated by the lines 17-17 of Figure 18;

Figure 18 is an end elevation partly in section of the ing mechanism on an enlarged scale, the section being ply-contracting mechanism of Figure 17, with the fingers being shown in retracted position, the scale being somewhat smaller than that of Figure 17; t

Figure 19 is'a fragmentary end elevation ofrthetplycontracting mechanism of Figures 17 and 18 showing the fingers contracted inwardly upon the plies, the view being on a still larger scale than that of Figure 18;

Figure 20 is'a perspective view showing the ply-engaging end of one of the fingers of theply-contractingmechw nism of Figures 1 7 l 9; l 1

Figure 21 is a somewhat diagrammatic view showing the ends of several ply-engaging fingers in the fully retracted position; r a a Figure 22 is a view similar to Figure 21 showing -the manner in which the ends of the fingers intermesh to form a continuous surface to engage the plies;

Figure 23 is a transverse sectional view of the plyexpanding'mandrel at the left of the building drum, the view being takenin the plane indicated by the lines 23-423 in Figure and larged scale;

s Figure 24 is a view similar to Figure 23 showing the same section of the ply-expanding mandrel but with the mandrel in the position of expanding the plies; and

Figure 25 is a transverse sectional view taken in the plane indicated by the lines 25-25 in Figure S and shown in the enlarged scale of Figures 23 and 24.

Figures 26 and 27 are diagrammatic sectional views; illustrating .the manner in which an spring'built according tome invention, such as that shown-in Figure 2, s l r da ivul asizsdi am d- Ifhe?present-invention is described'with respect tothe building of aIsingle convolution air spring of the type the telescoping movement magnitude in order to provide area which results and the desired change in the efiective from the flexing of the air spring. In the vulcanized condition, the wall thickness of the air spring, which is the thicknesses of the inner liner 26 and plies 12 and 13, is about 5 of an inch. 1' T:

According to the present invention, the air spring just described is molded from an unvulcanized or green air spring having a bell-shape such as that in perspective in Figure 2, which is characterized by a cylindrical'pop tion 27 of substantial length extending from adjacent the small bead and merging intoa flaring, slightly concave, portion 28 which extends outwardly and terminates in large bead 14. It will be noted that the cylindrical portion 27 turns inwardly in diameter to the small bead 15. An unvulcanized air spring of such shape is then molded to the shape shown in Figure l. The construction provides a desirable balance of strength and being shown on a somewhat ent flexibility. :1. r p

. The building drum generally The air spring of Figure 2 is built upon a cylindrical building drum indicated generally at 30 which may be considered as being divided longitudinally into three por tions. The left-hand portion 31, as viewed in the drawings, is expandable into conical form to formthe flaring portion 28 of the air spring. The central drum portion 32 is of fixed diameter and it forms the cylindrical portion 27 of the green air spring. The right-hand drum portion 33' actsas an extension of the central-portion 32"and provides a stitching surface for the end portions of the liner and of plies 12 and 13 which are later turned about the bead ring 25. I Initially the drum has the position shown in Figures illustrated in Figurel where'itis' shown assemblediri' to generally at 10, has a rubberized lplies' 12and '13 whichterrninate' in inex't'ensible beads 14 and 15 of different diameters. The large bead -14 is"secured to the'frame 17 of the-automobile bymeans of a reservoir assembly 18, while" the small bead 15 is secured to an arm 19, which helps to carry thevwheeldfljby =means" of a supporting member and associatedstructureindicated generally at21.-

When the wheel 20 strikes a bump in the road, the wheel and the amt 19 will rise upwardly with; respect tot he'tfrarne 17 causing the-air spring to be' compressed to a position such as that'in'dicated' by the dot-dash lines of'Figure l; and as'the': air springfc'ompresses," the-small bead l5fwill move upwardly towardand insome 'cases will pass through the large bead 14 in atelescoping move-- ment to reduce-both the volume and the effective crosssectional area of the air spring in such a manner as to effectively cushion the shock. r a

;In this compression stroke of-the air spring, the air pressures within thezairispringwill be 'in the order of about 100 to 150 pounds per square inch. In order to contain such pressures andyet be sufliciently flexible to undergo the type of flexing, such as that illustrated in from bead tobead, is about 9% inches, and the large bead 14 has an inside diameter of about 4%in'ches while thesmall bead 15 has an outside diameter. of about'3 inches, the difference in bead diameters being of this and stitched together to which is turned-about the bead ring 3-7 with the-left-hand drum section 31' in contracted position and with the'riglit-handdrum section 33 in position adjacentthe central portion 32. The innerliner 26' and-the plies lz and '13 are then laid "upon the drum form a cylindrical body having an end-portion 35 'which' e'xtends beyond the central section onto the right-handdrumsection 'for a distance of about 2 inches. This end portion provides the stoclc 25. It is accordl ingly necessary to turn this portion 35 radially inwardly.

I t ply-contracting. meehanis in aradially inward directionupon strict the pliestoa smaller diameter.

from' an outer diameter of about 2% inches, aslaid upon the drum, to a diameter ofabout-1%; inches to permit. the bead ring 25 to be set in place overthe plies against the shoulder of the drum. To .accomplish this,.a ply, turning or ply-contracting vmechanism, indicated. gener.-.: ally at 36, and .a bead-setting. mechanism, :indicated gen-.i erally at -37,are employed.

.. The ply-contracting mechanism m 35 consists of, two virtually identical units 38a and 38b, which will be referred to hereafter as the inner andoutei' iris units, respectively, each having a plurality of fingers 39- which are movable the plies to con-l M The inner unit 38a in its operative position, as shown in Figure 17, is located close to. the outer shoulder 40 of the building 32 so that the'ffin'g'ers of the unit will en-i drum section gage the plies close to the shoulder of the drum to force them inwardly with a controlled wrinkling-'o'fj'the plies, seeFigure17. i j "L The outer-unit 38b is operated independently of; the inner unit'and is speced axially'about /fi inch from the first unit toward the edge of the plies; it operates to con;

I tract the plies close to their end edges so as to counteract j ,In the present example, the length of the -nylon cords amount of wrinkling the tendency of the ply ends to springback toward'thcir' original diameter, this spring-back being apt to occur if only the inner iris unit 3811 is'used." Although acertain of the plies takes place as the iris units contract them, these wrinkles are later removed when the plies are turned back around the bead ring The assembly of the two 'iris'unit's to form a unitary construction may take any one of a number of forms. In the present example, the two units comprise a pair of central plates 41 and 42 which are secured together by machine screws 43, see Figure 17. The units are supported by and held fixed against rotation by mounting them on a supporting sleeve 44. The manner in which the sleeve 44 and his units are supported and moved into and away from operating position will be described later.

Since the iris units are virtually identical, only the inner unit 38a willbe described in detail. Where possible, the same reference numerals will be applied to corresponding parts of both iris units. I As best shown in Figures 17 and 18, the central plate 41 of iris unit 38a has a plurality of radial slots 47 which hold the fingers 39. The fingers are given their required radial movement by means of a cam ring 48 having a flanged edge construction 49 which enables it to be journalled upon the plate 41 in the manner shown in Figure 17. The cam ring has a limited rotational movement. upon the plate 41 which is translated into radial movement of the fingers 39 by axial pins 50 which are fixed to the fingers and which extend into diagonal slots 51 in the cam ring. The action is such that when the camring is turned clockwise, as viewed in Figure 18, the pins will be forced to move radially inwardly by the outer edges 52 of the slots until the pins strike the inner ends 53 of the slots, see Figure 19. When the cam ring is turned counter-clockise, the inner edges 54 of the slots will force the pins to travel outward along the slot to the outer ends 55 and thereby bring the fingers 39 back into their radially outermost positions.

Preferably the iris units are rotated by similar segmental gear arrangements comprising segmental gears 56 and 57 respectively extending over about 45 of arc and mounted on brackets 58 and 59 which are secured respectively to the fixed plate 41. The segmental gears are operated by the independent rotary air cylinders 60 and 61 acting through pinion gears 62 and 63. With this arrangement the iris units can operate either simultaneously or separately. By using pneumatic cylinders the pins 50 will act effectively as stop members when they strike the ends of the slots 47 and will thereby limit the positioning of the fingers 39 to the desired fully closed and fully opened positions. 7 p

The fingers 39 are shaped so that when they are fully closed they will intermesh with each other to produce a smooth, unbroken surface in contact with the plies. Each finger is about 2 inches long, about /2 inch wide and about /4 inch thick and is triangularly notched, as indicated at 65, at each side to a depth of about half the thickness of the finger with the notches extending to the ends of the fingers so as to produce the staggeredend effect best shown in Figure 20. These notches 65 permit the fingers to overlap each other at their ends at the extreme portion of their inward movement, see Figure 21 and particularly Figure 22. The ends of the fingers are also slightly concave across their ends. The result" is that, when the fingers are moved to the full limit of their inward movement, they define a complete and virtually uninterrupted circular (or rather cylindrical surface) to engage the plies, see also Figure 19-. This feature also tends to minimize the formation of wrinkles in the plies.

The drum section 33 and bead-setting mechanism and then the shaft 86 will end 69. whenthe drum sections 32 and 33 are. separated prior to the building operation.

After the drum section 33 has been withdrawn to the right, and the plies contracted as shown in Figure 9, the iris unit 38b is opened and the tubular member 68 is immediately moved to the left within the drum section to carry the bead ring over the ends of. the inturned plies. The iris unit 38a isthenopened and the tube is moved further to the left to set the bead' ring forcibly against the plies at the shoulder of the drum, see Figure 10. The bead ring will become'slightly embedded in and will adhere to the tacky plies so that it will remain in place when the tube is withdrawn. 7 I

The supporting structure for the ply-contracting and bead-setting mechanism The drum section- 33, the bead setting tubular member 68 and the iris units 38a and 38b are all supported by and moved into position by a carriage 71 which is mounted for longitudinal movement on a suitable base 72 at the right side of the drum, see Figures 3 and 4. The body of the carriage consists of the large sleeve 44, re ferred to above, on which the iris units are directly mounted. A pair of longitudinal flanges 73 and 74 which extend downwardly from the sleeve 44 each have pairs of rollers 75 journalled thereon, the rollers riding on longitudinal rails 76 at the sides of the base. The carriage is moved longitudinally by a threaded nut 78 which is secured to thecarriage and which engag'm a threaded rod 79 extending along one side of the base. The threaded rod is turned by an electric motor 80 operating through a speed reducer not shown. Rotating the [rod in, the one direction will cause the carriage to move leftwardly toward the building drum, while rotat ing it in the other direction will draw the carriage to the right awayfrom the building drum. I

The drum section 33 is bodily moved by the carriage but it also is given relative movement with respect to the carriage. To accomplish this, the drum section is journalled by means of a bearing 82 on a rightward extension 83 of the bead-setting tube 68 which in turn is mounted by bearings 84 and 85 on a central supporting shaft 86. The shaft 86 is supported within the sleeve 44 by spaced bearings 87 and 88. In order to move the drum section 33 and the bead setting member 68 independently of the carriage, the shaft 86 is moved in and with respect to the carriage by a pair of pneumatic cylinders 89 and 8911, which are mounted along the sides of the carriage and which act through a yoke 95 aifixed to the outer end of the shaft 86. Flexible conduits, not shown, supply air to the cylinders 89 and 89a.

As mentioned above, bead ring 25 is set in place by movement of the tubular member 68 to the left. To do this, it is necessary, in this embodiment of the invention, to provide relative movement of the drum section 33 and the bead-setting member. Accordingly, the beating 82 of the drum section has sliding movement onthe extension 83 as indicated in Figures Sand 7. Normally the drum section 33 is held in its full left position, as determined by the abutment of the radial flanges 90 and 91 on the section and bead-setting sleeve, respectively, by a coil spring 93 which'is positioned aroundextension 83 and compressed between bearing 82 and a thrust bearing 94 on the shaft. When the central shaft 86- is moved leftwardly to set the bead ring 25,.the drum section 33 will first strike the centraldrumsection 32'. continue to move to the left through the drum section until the bead ring is gseti this relative movement being permitted by the complies} sion of the coil spring 93. I f Y The ply turn-up mechanism a -f After the bead ring 25 has been set in place against the plies at the shoulder of drum section 3 2, thef'ply ends are turned up around the bead ring byun'eafis of an inflatable bag 97 which is expanded against 7, plies in such a manner as to turn the plies, first outwardly, as shown in Figure 12, and then axially around the beads as shown in Figure 13. The bag 97 is in the form. of a cylindrical rubber sleeve, the ends of which are clamped between two pairs of circular clamping plates 98, 99, 100 and 101, respectively, see Figure 7. The outer pair of plates 98 and 99 is fixed to a central or inner supporting shaft 102 of the drum by the arrange ment shown in Figure 7 in which the inner plate 99 of the pair has an axial flange 103 threaded upon the shaft and the outer plate 98 is threaded upon the external threads 104 of the axial flange 103.. The inner pair of plates 100 and 101 is mounted for sliding movement on the inner shaft 102, theinner plate 100 having an axial flange 105 having a sliding fit as indicated at 106 on the central shaft 102, the outer plate .101 being threaded upon external threads 108 of the axial flange 105. The construction and operating movements of the shaft 102 will be described in detail later. A coil spring 109, which encircles the shaft 102 and iscompressed between the pairs ofclamping plates,-serves to keep the plates apart and the bag 97 longitudinally extended as shown in Figure 7. The rubber bag or sleeve is thus normally stretched taut, by the spring 109 so that it can be housed within the drum section 32 when it is not in use.

The bag 97 is moved axially out of the drum section 32 into ply-turning and stitching position by moving the shaft 102 to the right until the end plates 100 and 101 are positioned within the bead ring 25, see Figure 11. In this movement of the bag, the bag will bring the ply ends out into approximately cylindrical form. In the next step, see Figure 12, the bag is inflated by introducing air into the bag under a pressure of about -20 pounds per square inch through a suitable conduit such as the passage 111, see Figure 7, which extends through the shaft 102 and opens into the bag by a lateral passage 112. After the bag has inflated outwardly to force the plies into an approximately radial position as shown in Figure 12, the end plates are brought closer together by moving shaft 102 back to the left while the sleeve 44 (which supports the iris units) is moved into position to restrict the outward inflation of the bag. After the bag is inflated'into contact with the interior surface of sleeve 44, the sleeve is moved to the left carrying the bag with it, and in doing so, the plies are forced tightly about the bead ring 25, See Figure 13. The air pressure in the bag is then relieved and the sleeve 44 is withdrawn to the right'asthe bag'is deflated and as the end plates are returned by spring 109 to the initial spacing of Figure 11. The collapsed bag is the drum section, its role of ply-turning and stitching completed. The required movements of the sleeve 44 are produced by moving the carriage 71 as described above.

The ply expandingmechanism for the large bead The left-hand drum section 31 has a heavy tubular body portion which is mounted as indicated at 114 for rotation upon a tubular driving shaft 115. The outer land portions will pass into then retracted within cylindrical surface of this drum section has six longitudinal slots 116 spaced about the periphery, each of which holds a bar 117 which is pivoted at its inner end upon a pin 118 which extends through a holedrilled through the body of the drum section. The outer surfaces of the pivotal bars 117 together with the longitudinal land portions 120 between the bars form. a substantially unbroken cylindrical surface upon which the inner liner andplies can bar '117 has a roller 121 which turns freely upon a pin bereadily assembled. Each 122 extending through the bar at its outer end and projecting beyond'the roller for an appreciable distance on each side of the-roller. j

- After the plies are assembled upon the drum, the lefthand portion of the air spring body is expanded into conical form by pivoting the wardly in a radial directicm The bars are given this bars 117 in-unison outpivoting movement by a conical expanding member or mandrel 125 which is moved axially toward and over the drum section 31 in such a manner that cam surfaces on the mandrel engage the rollers 121 at the outer ends of the pivotal bars and swing the bars outwardly about the pivotal pins 118.

The expanding mandrel is a conical'body having a number of slots 126 which correspond in number and in position to the pivotal bars and which are aligned axia1- ly therewith. Each slot 126 has a channel-shaped member 127 best shown in Figure 23 which is fixed to the body of the mandrel by any suitable means such as machine screws. The channels provide the cam surfaces, referred to above, which expand the pivotal bars. The bottom surfaces 128 of the channels provide cam tracks for the rollers 121 and the sides of the channels are slotted as indicated at 129, in the manner shown in Figure 23, to receive the pins 122 which support and guide the rollers. The pins 122 by their relatively snug fit within the slots 129 serve to hold the bars against the action of centrifugal force throughout the building cycle. The radial position of the bars 117 is thereby controlled by the position of the pins in the slots of the channel members. Thus when the drum is rotating in its initial position of Figure 5, the centrifugal force exerted on the bars is resisted by the pins 122 which at this moment are positioned in the inner ends of the slots. As the expanding of the bars takes place, the centrifugal force imparted to the bars is resisted by the continuous engagement of the pins with the edges of the slots 129 as they slide upwardly in the slots.

As will be explained later, the expanding mandrel is rotated by virtue of its interlocking engagement with drum section 31, it being noted from Figure 5 that in addition to the engagement of the bars 117 in the cam slots 126, the ends 1310f the channels 127 project into the slots 116 in the drum section.

In order to enable the expanding mandrel 125 to move completely over the drum section 31, the hub portion of the mandrel has six longitudinal holes 132 drilled to a depth slightly greater than the length of the land portions of the drum section. These holes are shown in dotted lines in Figure 5 and in endelevation in Figure 23. When the mandrel is moved in upon the drum, the the holes as the bars swing out, see Figure 24.

When the expansion of the drum section 31 is com plete, the 'outer surfaces of the pivotal bars 117 and the land portions a between the channels 127 of the expanding'm'andrel form a substantially unbroken conical surface to permit stitching of the plies about the large head 15 as indicated in Figure 16. Also, in the expanded position of the parts, circumferential notches in the bars 117 and in the land portions 125a of the mandrel form an unbroken annular groove 135 which serves to receive the large bead ring 24 and hold it'in position during the turning of the plies about the ring. This ply-turning operation will be described below. Preferably the large bead ring is held manually in the position where it will be seated in groove 135 as the drum is expanded.

After the plies have been turned and stitched about the bead ring 24, the drum sec on '31 is contracted by withdrawing themandrel 125 to the left as viewed. As this takes place, the cam slots 129 in the channels 127 will force the pins 122, and hence the outer ends of the pivotal bars, progressively inwardly until the pins reach the inner ends of the channel slots at which time the bars are fully retracted and the drum section is ready for the next building cycle.

The turning of the expanded plies between the outer ends'of the channels permit the operatto turn the expanded plies about the beading movement of a ply-turning tool 137 which comprises a sleeve having a number or circumferentially s aced areuat'e teeth 138 which p-iojeet from the end of the sleeve and fit between the channel members. Normally the teeth are positioned to the left with the ends of the teeth out of contact with the plies, see Figure 14. To turn the plies, the sleeve =1-37 is moved to the right as shown in Figure 15, by cylinders 160, 161 through yoke 162 and bearing 163, as shown in Figures 3, 4 and 6, until the teeth 138 engage the end portions of the ply portions which span the open spaces between the channels and turn the plies into a cylindrical form around the head 25. As these ply portions are turned, the entire circumference of the plies is of course also turned. The diameter of the sleeve 137 is such that the teeth will force the plies tightly around and against the bead ring 24 which remains in place in the groove 135 by virtue of its tight fit within the groove.

The ply-turning sleeve 137 is then withdrawn and the plies are stitched tightly about the'bead byv a conventional stitcher indicated at 139 in Figure 16. The stitching can be effectively performed because in this area the land portions 12511 of the mandrel and the pivotal bars of 'drumsection 117' form a continuous 'supporting'surface for the stitching operation.

. V The. supporting structure for the building drum Asmentioned'above the building drumsections 31 and 32 and their associated mechanisms are supported by the tubular drive shaft 115 which is cantilever supported in longitudinally spaced bearings 141 and 142 mounted on a suitable base 143 at the left side of the apparatus. The tubular drive shaft 115 is driven by an electric motor 144 operating through a suitable transmission which includes a pulley 145 secured to the end of the shaft. The expanding mandrel 125 is journalled on (and hence not driven by) the drive shaft by means of a bearing 156, see Figure 6. It will be recalled that the mandrel is driven in its rotary movement by its engagement with 'drumsection 31. j g

The central shaft 102 referred to above fits within the tubular shaft 115 and is supported thereby, the central shaft extending beyond the end of the drive shaft 115 where it terminates in a bearing 147, see Figures 3 and 4, which is supported by a yoke 148. The yoke 148 transmits the force of a pair of air cylinders 149 and 150 which are mounted on base 151 and which operate to move the central shaft longitudinally to'move the inflatable bag 97 into the operative position and bring it back to idle position. The bearing 147 is such as to transmit the axial thrust of theair cylinders and still permit the idling rotation of the central shaft within the drive shaft.

A rotary seal '152 at the end or the central shaft connects the passage 111, referred to above alternatively to a source of air under pressure or tea vacuum as may be desired in the operation ofth'e "stitching bag.

The expanding 'niaridfelv 125 is moved longitudinally on the hollow driveshaft 115 by a pair of air cylinders 153 and 154, see Figures 3 and 4, operating through a yoke 155 which is connected to the body of the mandrel through a bearing 156 which transmits the required axial force to mandrel while permitting it to rotate with the building drum.

The molding of the air spring The air spring which is assembled in the manner described above takes the form shown in Figure 2 after it is removed from the building drum. From this form it can be molded and vulcanized to the finished form of Figure l by confining it in a suitable three-part mold such as that shown in Figures 26-27. The green air spring is collapsed axially by forcibly bringing the mold sections 166, 167 and 169 together in a closing movement from open position while the air spring is progressively in flated outwardly by fluid under a pressure of about -20 pounds per square inch which enters the mold through conduit 170, see Figure 26 which shows the mold in an early stage of the closing movement and just as the inflation begins. When the mold is fully closed as shown in Figure 27 the air spring wall will have been forced out into contact with the mold and the beads will be clamped between appropriate molding surfaces, as shown. Thereafter the application of heat and pressure to the air spring completes the vulcanization.

While the invention has been described with reference to the manufacture of a specific air spring, it will be apparent that it can be adapted to the building of'many different types of air springs, differing in material, shape and dimensions. Thus, within relatively wide limitsyit is not necessarythat the air spring to be manufactured have any particular wall thickness, overall length bead diameter, or that it be made of specific materials. Many design features of the air spring building drum and asso ciated apparatus may likewise be varied and modified within the scope of the invention, the essential features of which are summarized in the appended claims.

What is claimed is:

1. Apparatus for manufacturing an air spring having a single convolution wall comprising a plurality of plies the" ends of which terminate in a large bead and a small bead, respectively, the small bead being ofa diameter enabling it to telescope completely through the large bead when said air spring is fully deflected, said apparatus comprising a normally cylindrical drum upon whichs'aid plies are assembled to form an initially cylindrical body, said drum having a diameter larger than the diameter of said small bead and smaller than the diameter of said large bead, means to withdraw a portion of said drum from a position of support for the "end portion of said cylindrical body leaving said end portion projecting axially from the remaining shoulder of said drum, means -to contract said one end portion radially inwardly and then around a substantially inextensible first bead ring to form said small bead and means to expand the other end portion radially outwardly and then around aseoond, substantially inextensible bead ring to form said large bead. 2. Apparatus according to claim 1 in which said means to contract includes expansible means to turn the plies back and radially outwardly about said first bead ring.

3. The apparatus of claim 2 in which said expansible means comprises an inflatable bag normally having a diameter substantially smaller than said bead ring, but inflatable outwardly to a diameter greater than the drum diameter. 7

4. The apparatus of claim 3 and an axially movable sleeve having a diameter substantially greater than said normal drum diameter, means to move said sleeve axially toward and over said drum to direct said outwardly turned plies and said inflated bag axially around said first bead nng.

5. Apparatus according to claim 1 in which the remain ing drum portion is supported on and driven by a tubular shaft and in which the means to contract includes an expansible bag mounted on a central shaft, said central shaft being positioned within said tubular shaft and movable axially with respect thereto.

6. Apparatus according to claim 5 in which said expansible bag comprises a rubber sleeve, a pair of plates clamping and sealing one end of said sleeve and aifixed to said central shaft and a second pair of plates clamping the other end of said sleeve and having a close sliding fit on said shaft, said pairs of plates and sleeve forming a substantially air-tight enclosure.

7. Apparatus according to claim 6 in which a coil spring is confined between said pairs of plates.

8. Apparatus for turning and stitching the ends of a cylindrical body of fabric plies about an inextensible bead ring after' said plies have been contracted inwardly over the shoulder of a supporting drum and after said bead ring has been set in place against said contracted plies at the shoulder of'said drum, said apparatuscomprising an inflatable sleeve, closure means at the ends of said sleeve forming a substantially airtight enclosure, said sleeve having a position within said contracted plies, a tubular member substantially larger than said cylindrical body, means to inflate said sleeve to turn said plies radially outwardly and to expand the wall of said sleeve into frictional contact with said tubular member, means to move said tubular member toward said cylindrical body'whereby said inflated sleeve carries said radially outwardly turned plies axiallyaround said head ring and into adhesive contact with said body.

9. Apparatus for turning and stitching the ends of a cylindrical body of fabric plies about an inextensible bead ring after said plies have been contracted radially inwardly over the shoulder of a supporting drum and after said bead ring has been set in place against said contracted plies at the shoulder of said drum, said apparatus comprising an inflatable, cylindrical sleeve, closure means at the ends of said sleeve forming a'substantially airtight enclosure, said sleeve normally being positioned withinsaid drum, means to move saidsleeve outside said drum into a position within said contracted plies to turn said plies partially in an axially direction, a tubular member substantially larger than said cylindrical body and telescoped over said inturned ends, means to inflate said sleeve against said plies to turn said plies radially outwardly and to expand the wall of said sleeve into frictional contact with the inner surface of said tubular member, means to move said tubular member toward said cylindrical body to carry said inflated sleeve and outturned plies axially around said bead ring and into adhesive contact with said body.

10. The apparatus of claim 9 and means to move said closure means toward each other as said sleeve is inflated.

. 11. Apparatus for turning and stitching the ends of a cylindrical body of fabric plies about an inextensible .bead ring after said plies have been contracted inwardly over the shoulder of a hollow supporting drum and after said bead ring has been set in place against said contracted plies at the shoulder of said drum, said apparatus comprising an inflatable, cylindrical sleeve, closure means at the ends of said sleeve forming an airtight enclosure, said sleeve and closure means being supported by a longitudinal shaft at the axis of said-drum and saidsleeve normally being positioned within said drum, means to move said sleeve outside said drum into a position within said contracted plies, a tubular member substantially larger in diameter than said cylindrical body, means to inflate said sleeve to turn said plies radially outwardly and to expand the wall of said sleeve into frictional contact with said tubular'member, means to. move said tubular member toward said cylindrical body whereby said inflated sleeve carries said outwardly turned plies axially around said head ring and into adhesive contact with said body. i

12. The method of manufacturing an air spring which comprises building 'an unwlcanized air spring having a cylindrical portion turned inwardly at one end in a radial direction and terminating in a head of lesser diameter than thediameter of said cylindrical portion andtmerging at the other end in an outwardly flared portion which terminates in a beadof substantially greater-diameter than' said cylindrical portion, exertingpressurev on the ends of said beads to collapse said air spring axially while inflating it outwardly with fluid pressure into contact with a confining mold to form a single convolution and thereafter subjecting said air spring to heat and pressure.

' 13. The method of manufacturing an air spring comprising a single convolution body terminating at its ends in a large bead and a small bead, respectively, which comprises assembling rubberized fabric plies into sub stantially cylindrical form;.turning (meet the ends of said form radially inwardly and then back around an inextensible ring to form said small bead, expanding the opposite portion of said cylindrical form into an outwardly flaring form, thereafter turning the end of said flared portion around an inextensible ring to form said large bead and then collapsing said air spring axially while inflating said air spring body outwardly into the form of a single convolution and subjecting the air spring to heat and pressure to vulcanize the same,

14. The method of manufacturing an air spring which comprises assembling rubberized fabric ply-material to form a body which is substantially cylindrical in form, contracting oneof the end portions of said body radially inwardly and then back outwardly about an inextensible ring having a diameter smaller than the'diameter of said body, expanding a substantial portion of said body, at the end opposite said contracted end portion, into outwardly flaring form and turning the extreme end portion of said expanded portion about an inextensible ring having a diameter appreciably greater than the diameter of said cylindrical body.

References Cited in the file of this patent UNITED STATES PATENTS 1,966,541 Denmire July 17, 1934 2,182,176 Maranville Dec. 5, 1939 2,208,540 Brown July 16, 1940 2,251,904 Breth et a1. Aug. 12, 1941 2,614,951 Iredell Oct. 21, 1952 2,614,952 Kraft Oct. 21, 1952 2,649,892 Appleby Aug. 25, 1953 2,669,281 Breth Feb. 16, 1954 2,715,931 Frazier Aug. 23, 1955 2,874,458 Smith Feb. 24, 1959 FOREIGN PATENTS 978,163 France Nov. 22, 1950 7 OTHER REFERENCES 1 7 Automotive Industries-Air Springs, Dec. s, 1951, pages 54-57. i

, UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent, No, 2371,2375 Februegy 14 1961 Herbert H Deis t' et a1 It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 4, line 5 after the first, occurrence inser sum of the -o Signed and sealed this 19th day of September 196;,

' (SEA L) Attest:

ERNEST SWIDER v DAVID L. LADD Attesting Officer Commissioner of Patents USCOMM-DC 

1. APPARATUS FOR MANUFACTURING AN AIR SPRING HAVING A SINGLE CONVOLUTION WALL COMPRISING A PLURALITY OF PLIES THE ENDS OF WHICH TERMINATE IN A LARGE BEAD AND A SMALL BEAD, RESPECTIVELY, THE SMALL BEAD BEING OF A DIAMETER ENABLING IT TO TELESCOPE COMPLETELY THROUGH THE LARGE BEAD WHEN SAID AIR SPRING IS FULLY DEFLECTED, SAID APPARATUS COMPRISING A NORMALLY CYLINDRICAL DRUM UPON WHICH SAID PLIES ARE ASSEMBLED TO FORM AN INITIALLY CYLINDRICAL BODY, SAID DRUM HAVING A DIAMETER LARGER THAN THE DIAMETER OF SAID SMALL BEAD AND SMALLER THAN THE DIAMETER OF SAID LARGE BEAD, MEANS TO WITHDRAW A PORTION OF SAID DRUM FROM A POSITION OF SUPPORT FOR THE END PORTION OF SAID CYLINDRICAL BODY LEAVING SAID END PORTION PROJECTING AXIALLY FROM THE REMAINING SHOULDER OF SAID DRUM, MEANS TO CONTRACT SAID ONE END PORTION RADIALLY INWARDLY AND THEN AROUND A SUBSTANTIALLY INEXTENSIBLE FIRST BEAD RING TO FORM SAID SMALL BEAD AND MEANS TO EXPAND THE OTHER END PORTION RADIALLY OUTWARDLY AND THEN AROUND ASECOND, SUBSTANTIALLY INEXTENSIBLE BEAD RING TO FORM SAID LARGE BEAD. 